When it comes to galaxies, the little guys do a lot of the work. Dwarf galaxies, amorphous blobs of only tens of millions of stars, were cranking out nearly a third of the new stars in the universe from about 8 billion to 10 billion years ago, according to new research posted June 17 on arXiv.org.

Previous research into star formation in the early universe has typically been biased toward massive galaxies because they’re brighter. The new observations with the Hubble Space Telescope show that dwarf galaxies were churning out enough stars to double their mass every 150 million years.